This invention pertains to a support structure for multiple tubes of a solar receiver panel. It pertains particularly to a support structure for multiple parallel vertical tubes for a solar flux receiver panel, which provides freedom for thermal expansion and contraction of the tubes in the solar receiver panel assembly.
Solar receiver panels utilizing a plurality of solar heated tubes containing a circulating heat transfer fluid are generally known. Heating of such panel tubes from a cold or ambient condition to a hot operating condition by incident solar heat flux causes the panel to expand both longitudinally and transversely, so that a panel support structure must permit sufficient movement of the tubes. Also, because of differences in heat flux to the tubes and fluid flow distribution in the tubes, tube expansion occurs at varying rates and extents. Thus, a suitable tube support structure must be able to accommodate such varying amounts of tube thermal expansion and contraction for the individual tubes, and yet stably support the tubes and the solar receiver panel in an effective and reliable manner.
Several support systems for solar heated tubes have been provided in the prior art. For example, U.S. Pat. No. 3,952,725 to Edmondson discloses a solar water heater in which parallel runs of continuous tubing are supported uniformly by metal foil and thermal insulation provided on the lower or shady side of the tubes. U.S. Pat. No. 4,144,875 to Bruno et al discloses a solar collector in which parallel tubes are uniformly supported by a formed heat conductive surface. U.S. Pat. No. 4,148,296 to Parlato discloses solar heating apparatus in which adjacent tubes carrying a fluid are supported at the tube opposite ends. Also, U.S. Pat. No. 4,261,334 to Matthews discloses a solar heat collector in which serpentine-shaped coils are supported by thermal insulation. However, the prior art apparently has not provided a solar panel tube support system in which multiple parallel tubes are each attached at an intermediate location to a common support rod so as to provide for substantial thermal expansion and contraction not only for the individual tubes but also for the panel assembly. Consequently, a need has existed for such a support system for arrays of multiple solar panel tubes, and such system is advantageously provided by this invention.